Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance at Mar. 31, 2019	$ 936,890	$ 451	$ (138,852)	$ 690,507	$ 399,473	$ (14,689)
Beginning Balance (in shares) at Mar. 31, 2019		45,122,985	1,903,241
Restricted stock units issued		$ 4		(4)
Restricted stock units issued (in shares)		373,430
Stock options exercised	1,261	$ 1		1,260
Stock options exercised (in shares)		36,289
Return of common stock to pay withholding taxes on restricted stock	(40,536)	$ (2)	$ (40,534)
Return of common stock to pay withholding taxes on restricted stock (in shares)		(158,426)	158,426
Stock compensation expense	13,121			13,121
Other comprehensive income (loss)	2,934					2,934
Net income	88,923				88,923
Ending Balance at Jun. 30, 2019	1,002,593	$ 454	$ (179,386)	704,884	488,396	(11,755)
Ending Balance (in shares) at Jun. 30, 2019		45,374,278	2,061,667
Beginning Balance at Mar. 31, 2020	$ 1,065,466	$ 450	$ (265,411)	739,133	602,482	(11,189)
Beginning Balance (in shares) at Mar. 31, 2020	45,008,687	45,008,687	2,533,374
Restricted stock units issued		$ 1		(1)
Restricted stock units issued (in shares)		124,749
Stock options exercised	$ 1,010			1,010
Stock options exercised (in shares)	31,000	31,488
Return of common stock to pay withholding taxes on restricted stock	$ (9,857)		$ (9,857)
Return of common stock to pay withholding taxes on restricted stock (in shares)		(52,515)	52,515
Stock compensation expense	9,298			9,298
Stock repurchase program	$ (11,310)	$ (1)	$ (11,309)
Stock Repurchased During Period, Shares	(67,649)	67,649	(67,649)
Other comprehensive income (loss)	$ 2,654					2,654
Net income	44,588				44,588
Ending Balance at Jun. 30, 2020	$ 1,101,848	$ 450	$ (286,577)	$ 749,440	$ 647,070	$ (8,535)
Ending Balance (in shares) at Jun. 30, 2020	45,044,760	45,044,760	2,653,538